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Self-Organization of InAs/InP Quantum Dot Multilayers. Navdeep Singh Dhillon. Overview. Regimes of 3-D self-organization in quantum dot layers described using Experimental observations for InAs/InP(001) system Atomistic Strain calculations - PowerPoint PPT Presentation
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Self-Organization of InAs/InP Quantum Dot Multilayers
Navdeep Singh Dhillon
Overview
Regimes of 3-D self-organization in quantum dot layers described using– Experimental observations for InAs/InP(001)
system– Atomistic Strain calculations
Pseudophase diagram developed to explain transition from vertically aligned to anti-aligned layers
Motivation
Periodicity and size uniformity of quantum dots grown in Stranski-Krastanov mode important for device applications
Detailed understanding of physical origin of phenomena prerequisite for obtaining the required 3-D arrangement for particular application
Stranski-Krastanov growth
InP(001) substrate
Low-Pressure Metal-Organic Vapor Phase Epitaxy in a cold-wall reactor
Stranski-Krastanov growth
InP substrate
InAs
3-7 ML of InAs is deposited
Stranski-Krastanov growth
InP substrate
InAs Islands
60 s treatment in TBAs/H2 ambient
The InAs monolayers form islands due to Interlayer Strain
Stranski-Krastanov growth
InP substrate
InAs Islands
Deposit Spacer layer and repeat
2 Regimes of Self-organization
Vertically Aligned (VA) Anti-Aligned (AA)
Quantum Dot Array Modeling
H Spacer Thicknessh QD heigthb QD baseD Lateral Spacing
C Vertically aligned point
A1, A2, A3Anti-aligned points
Experimental Results
Alignment depends mainly on H/D
Slight dependence on b/D
No direct dependence on h
Atomistic Strain Calculations
Keating’s valence force field method
Atomic coordinates relaxed using a conjugate-gradient algorithm until a minimum of elastic energy is found
16.6 < D < 29 nm 3.3 < b < 15.8 nm 1.2 < h < 3.6 nm
Conclusions
Self-organization of quantum dot multilayers– Spacer layer thickness (H)– Areal density of islands (D)– Lateral dimension (b) (to a lesser extent)
D b
H